Biodiesel have been considered as a possible substitute for petroleum diesel, because it possesses similar physical properties but lower pollutant gas emission than traditional diesel fuels. Biodiesel is a bio-fuel obtained by a transesterification reaction of vegetable oil or animal fat with a short-chain alcohol. Based on local availability, a wide variety of renewable feedstock can be utilised for synthesising biodiesel. Many are the benefits from replacing fossil fuels for biodiesel, specially the environmental advantages. Biodiesel is commonly blended with petroleum diesel. As the chemical composition of biodiesel differs greatly from petroleum diesel, biodiesel will interact differently than petroleum diesel with various materials. Therefore, the resistance of some elastomers should also be thoroughly analysed because of the importance of this kind of material for the automotive industry. Nitrile rubber (NBR) is used widely to fabricate vehicular hoses and gaskets, and these components come directly into constant contact with fuels when the engine is running. The difference in acrylonitrile content results in different polarities and mechanical properties of the resultant elastomer. As a result, it would be best to study the performance of various NBR elastomers to determine their chemical resistance when exposed to biodiesel. In this work, it will be studied the resistance of carboxylated-nitrile rubber (XNBR) and nitrile rubber (NBR) with different content of acrylonitrile in the presence of pure and diesel-blended biodiesel. The formulation and processing of NBR and XNBR will be carried out according to ASTM D3182. Tensile, tear and hardness properties will be conducted with immersed and non-immersed vulcanized samples according to their respective ASTM standards. The immersion tests (ASTM D471) will be performed at 70ºC for 70h at an oven. Furthermore, the fracture surface of test specimens will be analysed by scanning electron microscopy (SEM).